1. Field of the Invention
The present invention relates to a tension control method for a rolling stock section located between a front roll stand and a rear roll stand of a rolling train.
2. Description of the Related Art
In accordance with the prior art, slender rolling stock, such as bar steel and wire, is rolled in continuous rolling trains. When in these trains the rates of rotation of successive roll stands do not correspond to the continuity equation which is determined by the constant mass flow, tension or compression build up between the successive roll stands.
Tension and compression in the rolling stock have a negative influence on the cross-section tolerances, particularly the section width. Moreover, compression in the rolling stock leads to instabilities which produce so-called fluttering. In an extreme case, compression in the rolling stock may even lead to material ruptures and interruptions of the operation.
In order to achieve good finishing tolerances and to guaranty a safe rolling process, an efficient tension control is required.
In accordance with the prior art, primarily two control types are used for tension control, i.e., the so-called flow stoppage method and the looping method. For realizing both methods, a minimum distance between stands is required. When the distances between stands are too small, only a manual method of tension control is available in the prior art. By applying an impact or pressure on the rolling stock, the rolling train operator attempts to estimate the tension or compression present in the rolling stock based on his experience. This method of operation is subjective and very imprecise and also unreliable. Moreover, this method can only be carried out in certain time intervals. A control of the tension is not possible using this method.